This specification relates to the use of quaternary ammonium compounds containing at least one long hydrocarbon chain. The long-chain quaternary ammonium compounds can be used as additives for various wood preservatives to enhance certain properties of wood products. The long-chain quaternary ammonium compounds of the current application have little or no biocidal activity. Two benefits of the present wood preservation treatments are:                1) Reduction of the preservative loss when the treated wood is subjected to water and soil contacts, including copper based and other wood preservative systems.        2) Enhancement of the biological performance of wood preservative system.        
Quaternary ammonium compounds are widely used as biocides, surfactants, fabric softeners, anti-static agents, and hair conditioners. Related to the area of wood preservation and wood protection, one of the first reports on the fungicidal properties of quaternary ammonium compounds was made by Dunn in 1938 (C. C. Dunn, Proc. Soc. Exptl. Boil. Med., 37, 661, 1938). Reports on the use of quaternary ammonium compounds as wood preservatives first appeared in the 1960s. The efficacy of quaternary ammonium compounds as wood preservatives was reported by Butcher et al. (J. A. Butcher, A. F. Preston, and J. Drysdale, 1977, For. Prod. J. 27(7), 19; J. A. Butcher, and J. Drysdale, 1977, Mat. Und Org. 12(4), 271; J. A. Butcher, A. F. Preston, and J. Drysdale, 1979, N.Z. J. For. Sci., 9(3), 348).
ACQ® wood preservative, containing alkaline copper and quaternary ammonium compounds, was patented by Findlay and Richardson in North America (Can. Patent 1,146,704, U.S. Pat. No. 4,929,454) and by Sundman in Europe (European Patent 0089958, WO82/03817). Chemical Specialties Inc., Charlotte N.C. owns the rights for the patents resulting from the European patent and WO patent application. ACQ® is a registered trademark of Domtar Inc., exclusively licensed to Chemical Specialties Inc., Charlotte N.C., for quaternary ammonium-copper wood preservatives in North America. More recently, quaternary ammonium compounds with various carboxylate anions were described in European Patent 0906177.
The biocidal activities of quaternary ammonium compounds are related to the nature and length of their alkyl chains. In particular, relatively short chain alkyl quats such as didecyldimethylammonium chloride or short chain benzyl quats have been found to provide biocidal activity, while longer chain alkyls such as hexadecyl or longer have little or no biocidal activity in such structures. The most effective and commonly used quaternary ammonium compounds for the wood preservation industry have been alkylbenzyldimethyl ammonium compounds and didecyldimethylammonium compounds.
Long-chain quaternary ammonium compounds such as ditallowdimethylammonium chloride and dihydrogenatedtallowdimethylammonium chloride have little or no biocidal activity and are mostly used as fabric softeners, anti-static agents and hair conditioners. A recent patent (European Patent 1114704) claims waterproofing properties when long chain quaternary ammonium compounds are used in combination with biocidal quaternary ammonium compounds for wood treatments. The use of quaternary ammonium compounds and silicone binders for tissue paper was also described in European Patent 0 799 350.
A solvent-free wood preservative composition containing quaternary ammonium compounds was disclosed in WO 09939886. The quaternary ammonium compounds were said to serve as a dissolving mediator for the binding agent. In EP 0 293 556, a wood-protecting agent containing a water-soluble quaternary ammonium compound was disclosed. EP 0 293 246 described a composition containing a microbiocidally active quaternary ammonium compound. Amine oxides were used in wood preservative compositions (WO 0071311). It was suggested that the amine oxides had waterproofing properties.
One of the challenges facing providers of commercial wood preservative treatments using metal-based compositions is the potential loss of the metal component(s) during the service of the treated wood. The loss of the metal(s) is expected to reduce the biological efficacy of the chemical treatments as well as causing the lost metal to enter the surrounding environment. A recent U.S. patent (U.S. Pat. No. 6,843,837B2) has claimed that copper leaching could be reduced when certain vinyl-based polymers are added to the copper amine formulations.